This invention relates generally to exhaust gas analyzer apparatus preferably for diesel engines, of the type having an inlet connectable to the exhaust of a test engine and including filter means between the exhaust and the gas analyzer device. More particularly, the invention provides improved filter means in the form of an electrostatic separator for assuring delivery of particulate free exhaust gas to said gas analyzer device.
Accurate analysis of exhaust gases from an internal combustion engine, particularly diesel engines, is made difficult due to fine particulate matter such as soot carried by said gases. Such particulate matter quickly fouls the analyzer device. Where the gas analyzer operates on the infra-red absorption principle, the presence of such particulate matter in the gases delivered to the analyzer is of considerable disadvantage.
It is known that to counter such problem, filter means can be placed between the analyzer and the source of the exhaust gases. Since the particulate matter is of fine particle size, the filter medium used must also be fine so as to collect the small soot particles, for example. Accordingly, the filter medium soon becomes clogged, often blocked as to require frequent cleaning and/or replacement.
Thus, a need arises to provide means for removing the fine particulate matter from the exhaust gases prior to delivery to the gas analyzer device, whereby to obviate the disadvantages encountered in use of known devices, and which enables continuous operation of the gas analyzer without requiring change in the filter.
In addition, such filter means must be relatively simple in construction so as to enable inexpensive production and facile and rapid servicing. The particulate removal capacity of such filter device should be substantial so that continuous runs are possible without requiring change of filter or interruption for cleaning, if cleaning is possible.
Another difficulty encountered in the testing of exhaust gases involve the presence of water vapor or particles (droplets) carried by such gases. It would be highly desirable if the filter means employed would include means for separating such water vapor and/or particles from said gases before they reach the gas analyzer device. It would be advantageous also if the filter means could be provided with means for removing the separated particulate matter without dismantling the filter from the test line.